Development of an innovative monitoring system for vacuum circuit breakers - [News from Japan]

Switchgear used in power distribution systems is usually in service for more than 10 years. To ensure stable and highly- reliable operation, proper maintenance is of prime importance. In conventional maintenance of switchgear, preventive time-based maintenance (TBM) is carried out, involving periodic inspection at certain pre-determined intervals, e.g., once every six months, and replacement of nondurable components if appropriate. In order to conduct TBM properly, it is important to determine a maintenance time interval which balances cost and risk of failure. Usually this is very difficult. Alternatively, in condition-based maintenance (CBM) the replacement of each component is carried out following automated continuous inspection of its condition.